It has long been common practice for retail merchants to package merchandise purchased by their customers in paper bags to facilitate carrying the merchandise. Paper bags are easily refolded into their initial planar configuration by the customer after the bags are unloaded, and customers often refold and save their used paper bags for future use.
Paper bags are being rapidly replaced by plastic bags with hand loops or handles for easy carrying. Merchants are switching to plastic bags because they are light, strong, clean, require less storage space, and are less expensive than paper bags. Customers like the plastic bags because they are easy to carry and are more useful around the home than paper bags.
Plastic bags are more difficult to store than paper bags. Used plastic bag cannot be stored in stacks like new plastic bags and paper bags. Plastic bags have a planar configuration when manufactured but a used plastic bag cannot be returned to its initial flat or planar configuration. This is because the plastic has a limited amount of inherent "memory" which makes it impossible to return a used plastic bag to its initial shape. The limited "memory" partially "forgets" the initial flat shape of the bag when it is attempted to flatten a used plastic bag, causing the plastic in each used bag to arbitrarily and randomly protrude in different directions, making it impossible to stack used plastic bags.
Therefore, previous efforts to store used plastic bags have usually resulted in a fluffed up mess of entangled bags. Many used plastic bags are thrown away because there has not been a satisfactory way to store them.